Assessing episodic memory in rodents using spontaneous object recognition tasks.

Models of episodic memory are successfully established using spontaneous object recognition tasks in rodents. In this review, we present behavioral techniques devised to investigate this type of memory, emphasizing methods based on associations of places and temporal order of items explored by rats and mice. We also provide a review on the areas and circuitry of the medial temporal lobe underlying episodic-like memory, considering that a large number of neurobiology data derived from these protocols. Although spontaneous recognition tasks are commonplace in this field, there is need for careful evaluation of factors affecting animal performance. Such as the ongoing development of tools for investigating the neural basis of memory, efforts should be put in the refinement of experimental designs, in order to provide reliable behavioral evidence of this complex mnemonic system.

Rats recognize spatial and temporal attributes in a new object recognition memory task with multiple trials.

BACKGROUND: Episodic-like memory tasks based on the spontaneous exploration of objects are commonly applied in one-trial protocols. However, multiple-trial designs are known to reduce animal numbers and data variance, providing faster accumulation of data. NEW METHOD: In this study, we devised a new object recognition memory task for rats that carry out multiple trials per session. We developed three types of continual trial tasks: a longer protocol, a shorter protocol, and a protocol in which the experimental session was divided into two days. RESULTS: In our design, rats expressed temporal and spatial memory, but not what-where-when content integration. We found that shorter protocols were more efficient to evaluate memory capabilities. COMPARISON WITH EXISTING METHODS: To the best of our knowledge, it is the first object recognition task with multiple trials that simultaneously assess the temporal and spatial aspects of episodic-like memory. CONCLUSIONS: We suggest that our task is suitable for the simultaneous measurements of brain functions related to spatial and temporal attributes in rats.

Conspecific Presence Improves Episodic-Like Memory in Rats.

A number of studies have provided evidence that animals, including rats, remember past episodes. However, few experiments have addressed episodic-like memory from a social perspective. In the present study, we evaluated Wistar rats in the WWWhen/ELM task as single setups and in dyads, applying a long retention interval. We also investigated behaviors that could subserve the emergence of this type of memory. We found that only rats tested in the social setting were able to recollect an integrated episodic-like memory that lasted 24 h. Additionally, rats in dyads presented higher levels of exploration during the task. When exposed to the testing environment, the dyads exhibited affiliative behavior toward each other and presented fewer anxiety-like responses. Our findings indicate that the presence of a conspecific could act as a facilitating factor in memory evaluations based on spontaneous exploration of objects and provide empirical support for applying more naturalistic settings in investigations of episodic-like memory in rats.

Bebês: o irresistível poder da graciosidade. Um estudo sobre o significado evolutivo dos traços infantis / Babies: the irresistible power of cuteness. A study concerning the evolutionary function of infantile traits

Os bebês, em geral, despertam ternura e comportamentos de cuidado nas pessoas. O objetivo deste trabalho foi discutir a atração provocada pelos traços infantis, tendo como referencial teórico os quatro níveis de explicação de Tinbergen. Do ponto de vista dos mecanismos que desencadeiam essa atração neonatal, avaliamos a importância da aparência do infante para eliciar as respostas de cuidado parental. Considerando a função adaptativa desta característica, discutimos os processos evolutivos que moldaram as preferências pelos atributos infantis, além da história filogenética do favoritismo pelos sinais morfológicos de filhotes. Apresentamos, ainda, dados sobre o desenvolvimento deste traço comportamental ao longo da vida. Tomadas em conjunto, estas informações provêem uma análise de por que achamos os bebês tão irresistíveis.(AU)

Babies generally elicit tenderness and caretaking behaviors on people. The aim of this study is to discuss the attraction towards babyish features, taking Tinbergen's four questions as a theoretical benchmark. Concerning the mechanisms implicated in this neonatal attraction, we evaluated the importance of children´s morphology on eliciting parental responses. Considering the adaptive function of this characteristic, we discuss the evolutionary process that shaped the preferences towards infantile traits as well as the phylogeny of the preference towards infant´s morphological traits. It was also presented data about the development of this behavioral trait across life span. The information provided here suggests a reason why we find babies such irresistible creatures.(AU)

Bebês: o irresistível poder da graciosidade. Um estudo sobre o significado evolutivo dos traços infantis / Babies: the irresistible power of cuteness. A study concerning the evolutionary function of infantile traits

Os bebês, em geral, despertam ternura e comportamentos de cuidado nas pessoas. O objetivo deste trabalho foi discutir a atração provocada pelos traços infantis, tendo como referencial teórico os quatro níveis de explicação de Tinbergen. Do ponto de vista dos mecanismos que desencadeiam essa atração neonatal, avaliamos a importância da aparência do infante para eliciar as respostas de cuidado parental. Considerando a função adaptativa desta característica, discutimos os processos evolutivos que moldaram as preferências pelos atributos infantis, além da história filogenética do favoritismo pelos sinais morfológicos de filhotes. Apresentamos, ainda, dados sobre o desenvolvimento deste traço comportamental ao longo da vida. Tomadas em conjunto, estas informações provêem uma análise de por que achamos os bebês tão irresistíveis.

Babies generally elicit tenderness and caretaking behaviors on people. The aim of this study is to discuss the attraction towards babyish features, taking Tinbergen's four questions as a theoretical benchmark. Concerning the mechanisms implicated in this neonatal attraction, we evaluated the importance of children´s morphology on eliciting parental responses. Considering the adaptive function of this characteristic, we discuss the evolutionary process that shaped the preferences towards infantile traits as well as the phylogeny of the preference towards infant´s morphological traits. It was also presented data about the development of this behavioral trait across life span. The information provided here suggests a reason why we find babies such irresistible creatures.